P0117 on Toyota: How to Diagnose & Fix
Engine Coolant Temperature Sensor Circuit Low
1 Toyota model · 1 documented issue · 1 critical · $250-$800 repair
P0117 on Toyota by model: symptoms, diagnosis and fix
The Prius V uses an electric water pump (like all Gen 3 Prius-based vehicles) rather than a belt-driven mechanical pump. The electric pump motor can fail without warning, causing rapid engine overheating. Unlike a belt-driven pump where you'd hear squealing before failure, the electric pump simply stops. The vehicle may overheat within minutes in traffic. Toyota issued a recall for some Prius models but Prius V coverage varies by production date.
Common Symptoms
- Engine temperature climbing rapidly with no warning
- Red engine temperature warning light
- No coolant circulation (heater blows cold with engine hot)
- Steam from under hood
- Engine entering limp mode and shutting down
How to Fix
Replace the electric water pump assembly (Toyota 161A0-29015). The pump is located on the lower-left side of the engine and is accessible without major disassembly. Replace the thermostat and flush the cooling system during the repair. Some owners carry a spare pump as a precaution since failure is sudden and strands the vehicle.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- Toyota 161A0-29015 electric engine water pump assembly
replace a confirmed failed electric engine water pump and restore/bleed the engine cooling circuit Fitment/availability: 2012-2017 Prius v 1.8L 2ZR-FXE engine cooling circuit; replaces 161A0-39015 and is not the inverter coolant pump Fit…
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Owner tips & cautions
- TipIf the temperature gauge starts climbing suddenly, pull over IMMEDIATELY and shut off the engine — the Prius V overheats extremely fast without the water pump
- WarningDo not continue driving with an overheating Prius V even for a few minutes — the aluminum engine warps heads rapidly and can require a full engine replacement
P0117 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P0117 mean on a Toyota?
P0117 stands for "Engine Coolant Temperature Sensor Circuit Low." This code means the engine coolant temperature (ECT) sensor is reading too low a voltage, which the computer interprets as an impossibly high coolant temperature. In most cases this is an electrical fault — such as a short to ground in the wiring — rather than the engine actually overheating. The coolant temperature signal affects fuel mixture, cooling fans, and other functions, so a bad reading can cause poor running, hard starting, or fans running constantly. The fault is usually in the sensor or its wiring. On Toyota it is documented across 1 model: Prius V.
What are the most common causes of P0117?
The most common causes of P0117 are: Faulty engine coolant temperature sensor, Short to ground in the sensor signal wire, Damaged or corroded wiring/connector at the sensor, Coolant contamination affecting the sensor, Poor electrical ground, Faulty PCM/ECM (less common). The specific cause varies by vehicle.
How much does it cost to fix P0117 on a Toyota?
Published repair estimates on Toyota range from $250 to $800 depending on the model and root cause. If an issue mentions a recall or campaign, check your VIN with the manufacturer or NHTSA and confirm eligibility and coverage with a dealer.
Looking for P0117 on a different make?
View P0117 across all makes →Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.